The Law of Cosines: What is this about?
A Mathematical Droodle


This applet requires Sun's Java VM 2 which your browser may perceive as a popup. Which it is not. If you want to see the applet work, visit Sun's website at, download and install Java VM and enjoy the applet.

What if applet does not run?

The applet could serve to demonstrate the Law of Cosines and also the fact that the centers of the squares constructed (externally) on the sides of a parallelogram form a square, which is known as one of V. Thebault's theorems.


  1. R. Nelsen, Proofs Without Words, MAA, 1993, p. 19

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